1. Field of the Invention
The present invention relates to cycle vehicles, such as scooters or bicycles with two wheels and other related vehicles having more or fewer wheels. More specifically, the present invention relates to powered and/or power-assisted versions of cycle vehicles.
2. Description of the Related Art
Motors, including electric motors, have long been used to power lightweight vehicles such as scooters or bicycles. Various designs have been proposed to couple a motor to the bicycle as well as to transfer the power from the motor to the wheels which contact the ground. Various locations for the motor have been proposed and various attachment schemes. Some have described placing a motor on a rack above the rear wheel, while others have placed a drive unit below the seat and others have attached a motor bracket to the wheel itself. Frequently, the power system will be attached to the existing bicycle frame by clamping the motor to one of the existing tubes of the frame. Various methods proposed in the prior art for transferring power from the motor to the wheels include the drive systems, chain drive systems, and gear drive systems.
Difficulties presented by various systems include problems related to aligning or maintaining alignment of the motor with the wheel it is coupled to, difficulties in removing the wheel or reinstalling the wheel during maintenance, and creating a system that is small enough, light enough, and inexpensive enough to be suitable for widespread use. For example, when the motor bracket is attached directly to the wheel, removal, installation, and handling of the wheel during maintenance procedures can be awkward due to the presence of a heavy object pivoting around the axle of the wheel. Such a system also interferes with accessing the spokes, the hub, and the bearings in cases where these require servicing. Attachment devices in which the motor is clamped to tubes, such as the existing frame tubes, require a separate step to properly align the motor. Due to the forces involved with the presence of the motor, it is not unusual for the motor to twist out of alignment in such clamp arrangements during operation or if bumped, requiring realignment for optimum operation.
In addition, accurate and repeatable relative location of drive and driven portions of belt, chain or gear systems is important to achieve reliable operation of these systems. Improper adjustment of the proximity can result in chains or belts falling off, increased resistance, increased wear of parts, and unreliable transmission of drive forces. Existing electric bicycles or scooters employ mounting arrangements for the motor or other drive unit that are overly complex, difficult to adjust or maintain and expensive to manufacture.